Video Acceleration API (VA API) is an open source software library ("libVA") and API specification which enables and provides access to graphics hardware (GPU) acceleration for video processing on Linux and Unix based operating systems. Accelerated processing includes video decoding, video encoding, subpicture blending and rendering. Using VA API (GPU acceleration), playing H.264 videos for example should take some load of the CPU thus making the playback run more smoothly and with less CPU usage.
Like we told you when VLC 1.1.0 was out, there's no proper way of installing it with VA-API (GPU acceleration) in Ubuntu 10.04 Lucid Lynx and older because of the dependencies it requires - compiling it against newer ffmpeg packages would break all other packages which need ffmpeg (like video editors, other media players and so on).
But that was obviously possible for Ubuntu 10.10 Maverick Meerkat - and today VLC 1.1.2 with GPU acceleration was finally uploaded to the official Ubuntu 10.10 repositories.
To use VLC with VAAPI support, Nvidia users also have to install the vdpau-video package from the official Ubuntu repositories:
sudo apt-get install vdpau-va-driver
I'm not sure what packages you need to install if you're not using an Nvidia graphics card - if you do know, please let us know in the comments.
Then, to use VLC with GPU acceleration, simply upgrade to the latest VLC 1.1.2 and ffmpeg:
sudo apt-get update && sudo apt-get upgrade
Important: the VLC 1.1.2 package in Ubuntu 10.10 Maverick Meerkat has not been built yet so you'll have to wait a bit until you can upgrade (see its status here).